Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductor layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon.
The semiconductor industry continues to improve the integration density of various electronic components (e.g., transistors, diodes, resistors, capacitors, etc.) by continual reductions in minimum feature size, which allow more components to be integrated into a given area. These smaller electronic components also, in some instances, require smaller packages that utilize less area than packages of the past.
Package on package (PoP) technology is becoming increasingly popular for its ability to allow denser integration of integrated circuits into a small overall package. PoP technology is employed in many advanced handheld devices, such as smart phones. While PoP technology has allowed for a lower package profile, the total thickness reduction is currently limited by the solder ball joint height and the distance between adjacent joints, referred to as the pitch. Dies are sometimes mounted to an interposer substrate or other packaging carrier via a mounting conductor such as a ball grid array, land grid array, pin array, or the like. In some instances, an undermount filler or underfill may be applied between the die and the interposer PC board to fill the spaces between the mounting conductors.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.